This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The objective of this project is to determine how the distal processes of nerve cells regulate their protein levels after injury. These 'axonal processes'are needed for long-range communication in the brain and spinal cord. If these processes are disrupted, communication ceases and function of the brain and spinal cord is lost. Improving regeneration of injured axonal processes will restore function to the brain and spinal column. Several lines of evidence indicate that distal axonal processes can autonomously regulate levels of proteins needed for regeneration through modulating synthesis and degradation of these proteins locally. Until recently we have had no means to dissect the proteome of regenerating axons, since the materials available for study are exceptionally limiting and most often contaminated with other cellular constituents. We will take advantage of an axonal preparation that our laboratory has developed and the high sensitivity proteomics applications of the UCSF Mass Spectrometry Facility to determine how the precursors of axonally synthesized proteins are targeted for transport into axons and what becomes of the protein products encoded by these precursors. We will use affinity purification of mRNA: protein complexes to identify the proteins needed for transport of the mRNA precursors into axons. We will use recently available labeling approaches to isolate proteolytic substrates from axons for identifying proteins that are subjected to degradation in axons. Integrating these data with ongoing axonal mRNA profiling from our laboratory will provide a systematic view of protein dynamics of distal axons. Ultimately, these studies will provide us with a unique perspective of axonal biology that has not been feasible until now and should lead to novel strategies for accelerating regeneration after traumatic injury of the brain and spinal cord.